1. Field of the Invention
The invention relates to a pressure regulating earplug for controlling the rate of change of pressure in a person's ear which occurs typically during take offs and landings of airplanes, and more specifically, to an earplug which is designed to lessen the effects of congestion of the Eustachian tube of an airplane passenger, or the like, during a change in altitude.
2. Art Background
The middle ear is an air-filled cavity that connects to the outside environment via the Eustachian tube. Under normal conditions, there is no difference between the air pressure in the outside environment and the middle ear. This condition is illustrated in FIG. 1 which is a schematic drawing of the ear, and shows that under normal conditions there is no pressure difference across the eardrum. However, when there is a change in air pressure, such as what an airplane passenger experiences during take-off and landings, there is a difference in the air pressure between the middle ear and the outside environment, the difference in pressure equilibrating over time. Under conditions in which such a pressure differential exists, the Eustachian tube acts as a valve between the outside environment and the middle ear. In this capacity, the Eustachian tube opens for a fraction of a second in response to swallowing or yawning, allowing airflow through it so that the pressure differential between the outside environment and the middle ear equilibrate.
During the ascent of an airplane, the air pressure in the outside environment, that is, the environment inside the airplane and outside the middle ear, is less than that of the pressure inside the middle ear. Under these conditions, the positive relative pressure in the middle ear forces air out of the Eustachian tube thereby lowering the pressure inside the middle ear to the same pressure as the outside environment. If the Eustachian tube is blocked, as described more fully below, the positive pressure in the middle ear applies pressure to the ear drum, as shown schematically in FIG. 2, causing it to bow outward toward the external ear cavity.
Conversely, during the descent of an airplane, the air pressure in the outside environment is greater than that of the pressure inside the middle ear. Under these conditions, the negative relative pressure in the middle ear causes an airflow from the outside environment through the Eustachian tube and into the middle ear, thereby increasing the pressure inside the middle ear to the same pressure as the outside environment. Again, under condition in which the Eustachian tube is blocked, the negative pressure in the middle ear causes deformation of the ear drum, bowing it inward toward the middle ear, as shown schematically in FIG. 3.
Under normal circumstances, when there is no or little blockage of the Eustachian tube, as the pressure differential increases across the ear drum between the middle ear and outside environment, voluntary swallowing and/or chewing releases the pressure through the Eustachian tube.
Individuals sometimes develop colds, or suffer from allergies, respiratory infections, or other medical conditions wherein the Eustachian tubes become swollen thereby partially blocking the airflow through the tubes. In the case of airline passengers and others who are experiencing changes in altitude, the flow of air through the Eustachian tubes is restricted so that a pressure differential between the outside environment and the middle ear may persist for an extended period of time. As indicated above, these pressure differentials are believed to primarily affect the ear drum, causing it to distend, as shown in FIG. 2, or to bow inward toward the middle ear canal, as shown in FIG. 3, depending upon the pressure differential between the middle ear and outside environment. The Eustachian tube blockage prevents the equilibration of the middle ear and outside environment pressures, or delays it. During such pressure differential, as a result of the deformation of the ear drum, there is pain, or at least discomfort to the airplane passenger.
It would thus be desirable to regulate the pressure in the external environment so that the mount of time that the ear drum is deformed is decreased, and the resultant pain is decreased. No one has heretofore attempted to control the pressure differential between the middle ear and the outside environment in order to alleviate the pain caused by such pressure differential as described above.
A number of different types of earplugs have been designed for the purpose of attenuating sound to protect the user from damage which may be caused by loud noise, music or the like. Some of these plugs are made of silicone and can form an air tight seal in the ear canal. Others are made of a combination open- and closed-cell foam that do not seal the ear canal. A few of these prior art plugs allow rapid equalization of air pressure to reduce discomfort caused by air pressure differences between the ear canal and ambient when the ear plug is inserted into the ear canal, or when the ambient pressure changes. However, none of these plugs are designed to regulate the rate of pressure change in the ear canal, as in the present invention.
U.S. Pat. No. 3,736,929, issued to Allen William Mills ("the '929 patent"), is representative of the prior art which allow rapid equalization of air pressure. The '929 patent discloses an earplug formed of highly elastic material, with a hollow tube partially occluded with silicone grease, or a rod made of foamed plastic placed along the long axis of the earplug. The hollow tube or the rod allow rapid pressure equalization across the earplug. However this device, when used with the silicone grease, is not designed to accommodate the pressure differential caused by an altitude change, because as a result of the geometries of the system as shown, the silicone grease would be ejected from the tube.
U.S. Pat. No. 2,437,490, issued to Norman A. Watson, et al. ("the '490 patent"), is also representative of the prior art. The '490 patent discloses a hollow, elongated plug with an insert that occludes the hollow portion of the plug. The insert is packed with acoustical insulation material which attenuates sound and permits rapid equalization of the air pressure at the opposites ends of the plug.
Thus, it is dear from the foregoing background that none of the prior art ear plug devices are designed or intended to regulate the change in pressure between the middle ear and the external environment, which is the intention and application of the present invention.